Mn-Doped-Iron Sulfide as Long-Term Stability Anode for High-Performance Sodium-Ion Batteries at Wide Temperature and High-Rate Conditions

Iron-based sulfides are promising anode materials for sodium-ion batteries (SIBs) due to high theoretical capacities, but their short cycle life—caused by volume expansion and polysulfide shuttle effect—limits wide-temperature applications. To solve this, a novel three-dimensional MFS@rGO composite anode was prepared via one-step solvothermal method followed by annealing sulfurization, composed of Mn-doped Fe 7 S 8 (MFS) embedded in nitrogen-doped reduced graphene oxide (N-doped rGO). Mn doping enlarges Fe 7 S 8 lattice spacing, reducing Na⁺ diffusion resistance to boost ionic conductivity and Na storage. DFT calculations confirm Mn increases Fermi-level electronic density, lowers Na⁺ migration energy barrier, and accelerates ion transport. N-doped rGO builds a stable conductive network and synergizes with Mn to suppress shuttle effect and alleviate volume expansion, enhancing structural stability. Benefiting from this synergy, MFS@rGO performs well at −40–60 °C: 282.71 mAh g −1 after cycling at −40 °C, 310 mAh g −1 over 500 cycles at −20 °C, 450 mAh g −1 over 1000 cycles (60 °C, 2 A g −1 ). At room temperature, it retains 407.09 mAh g −1 ; over 100 cycles (1 A g −1 ); even at 50 A g −1 , it maintains 206.14 mAh g −1 over 100,000 cycles with negligible degradation. It also works well in full cells, offering a strategy for high-performance SIBs under extreme conditions.